Before we go on to make a bigger splash, it's worth noting in passing that titles are profoundly generic. There's nothing unusual in this as it applies to the other media equally. The reader and buyer uses certain cues; expects to see them. The creative talent takes a risk if they don't meet those expectations.
Everything is packaged to a demographic. Even if that demographic is an alternative one or specialist in nature or proclivity. There are common themes that slowly alter over time but show their influence in an unbroken line.
Covers depicting cute moppets invariably show them doing something humorous. Women, on the other hand, who are heroic or derring-do have covers to match.
Even the talent gets a reputation that publishers can take to the bank. Artists like macabre Mike Ploog or "Ghastly" Graham Inglesand writers like this guy.